1 files changed, 139 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Scalar/LowerAtomic.cpp b/contrib/llvm/lib/Transforms/Scalar/LowerAtomic.cpp
new file mode 100644
index 0000000..9087b46
--- /dev/null
+++ b/contrib/llvm/lib/Transforms/Scalar/LowerAtomic.cpp
@@ -0,0 +1,139 @@
+//===- LowerAtomic.cpp - Lower atomic intrinsics --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers atomic intrinsics to non-atomic form for use in a known
+// non-preemptible environment.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "loweratomic"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Function.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/IRBuilder.h"
+using namespace llvm;
+
+static bool LowerAtomicIntrinsic(IntrinsicInst *II) {
+  IRBuilder<> Builder(II->getParent(), II);
+  unsigned IID = II->getIntrinsicID();
+  switch (IID) {
+  case Intrinsic::memory_barrier:
+    break;
+
+  case Intrinsic::atomic_load_add:
+  case Intrinsic::atomic_load_sub:
+  case Intrinsic::atomic_load_and:
+  case Intrinsic::atomic_load_nand:
+  case Intrinsic::atomic_load_or:
+  case Intrinsic::atomic_load_xor:
+  case Intrinsic::atomic_load_max:
+  case Intrinsic::atomic_load_min:
+  case Intrinsic::atomic_load_umax:
+  case Intrinsic::atomic_load_umin: {
+    Value *Ptr = II->getArgOperand(0), *Delta = II->getArgOperand(1);
+
+    LoadInst *Orig = Builder.CreateLoad(Ptr);
+    Value *Res = NULL;
+    switch (IID) {
+    default: assert(0 && "Unrecognized atomic modify operation");
+    case Intrinsic::atomic_load_add:
+      Res = Builder.CreateAdd(Orig, Delta);
+      break;
+    case Intrinsic::atomic_load_sub:
+      Res = Builder.CreateSub(Orig, Delta);
+      break;
+    case Intrinsic::atomic_load_and:
+      Res = Builder.CreateAnd(Orig, Delta);
+      break;
+    case Intrinsic::atomic_load_nand:
+      Res = Builder.CreateNot(Builder.CreateAnd(Orig, Delta));
+      break;
+    case Intrinsic::atomic_load_or:
+      Res = Builder.CreateOr(Orig, Delta);
+      break;
+    case Intrinsic::atomic_load_xor:
+      Res = Builder.CreateXor(Orig, Delta);
+      break;
+    case Intrinsic::atomic_load_max:
+      Res = Builder.CreateSelect(Builder.CreateICmpSLT(Orig, Delta),
+                                 Delta, Orig);
+      break;
+    case Intrinsic::atomic_load_min:
+      Res = Builder.CreateSelect(Builder.CreateICmpSLT(Orig, Delta),
+                                 Orig, Delta);
+      break;
+    case Intrinsic::atomic_load_umax:
+      Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Delta),
+                                 Delta, Orig);
+      break;
+    case Intrinsic::atomic_load_umin:
+      Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Delta),
+                                 Orig, Delta);
+      break;
+    }
+    Builder.CreateStore(Res, Ptr);
+
+    II->replaceAllUsesWith(Orig);
+    break;
+  }
+
+  case Intrinsic::atomic_swap: {
+    Value *Ptr = II->getArgOperand(0), *Val = II->getArgOperand(1);
+    LoadInst *Orig = Builder.CreateLoad(Ptr);
+    Builder.CreateStore(Val, Ptr);
+    II->replaceAllUsesWith(Orig);
+    break;
+  }
+
+  case Intrinsic::atomic_cmp_swap: {
+    Value *Ptr = II->getArgOperand(0), *Cmp = II->getArgOperand(1);
+    Value *Val = II->getArgOperand(2);
+
+    LoadInst *Orig = Builder.CreateLoad(Ptr);
+    Value *Equal = Builder.CreateICmpEQ(Orig, Cmp);
+    Value *Res = Builder.CreateSelect(Equal, Val, Orig);
+    Builder.CreateStore(Res, Ptr);
+    II->replaceAllUsesWith(Orig);
+    break;
+  }
+
+  default:
+    return false;
+  }
+
+  assert(II->use_empty() &&
+         "Lowering should have eliminated any uses of the intrinsic call!");
+  II->eraseFromParent();
+
+  return true;
+}
+
+namespace {
+  struct LowerAtomic : public BasicBlockPass {
+    static char ID;
+    LowerAtomic() : BasicBlockPass(ID) {
+      initializeLowerAtomicPass(*PassRegistry::getPassRegistry());
+    }
+    bool runOnBasicBlock(BasicBlock &BB) {
+      bool Changed = false;
+      for (BasicBlock::iterator DI = BB.begin(), DE = BB.end(); DI != DE; )
+        if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(DI++))
+          Changed |= LowerAtomicIntrinsic(II);
+      return Changed;
+    }
+  };
+}
+
+char LowerAtomic::ID = 0;
+INITIALIZE_PASS(LowerAtomic, "loweratomic",
+                "Lower atomic intrinsics to non-atomic form",
+                false, false)
+
+Pass *llvm::createLowerAtomicPass() { return new LowerAtomic(); }